The present invention relates to apparatus for controlling an electronic flash, and more particularly, to camera apparatus having an exchangeable lens barrel which is provided with a light receptive element for receiving, when the barrel is mounted on the photographic camera body, the reflected imaging light rays of an object field. The light is reflected from the light sensitive film surface after passing through the objective lens and the iris aperture of the lens barrel at the time of an exposure. A current generated by the light receptive element is integrated by an electronic flash lighting circuit in the camera or in a separately housed electronic flash device, and when the integrated voltage reaches a certain predetermined level, the electronic flash tube is extinguished by the electronic flash circuit.
In electronic flash photography, electronic flash devices of the automatic light adjusting type are well known, and which devices receive the reflected light from an object illuminated by an electronic flash for controlling the lighting time of the electronic flash generating device, such as an electronic flash tube. Nevertheless, in flash photography, the factors by which an exposure is determined include the iris aperture setting of the objective lens in the camera and the sensitivity of the film, as well as the brightness of an object which is illuminated by the flash device.
Therefore, in such automatic light adjusting means as described above, even if a light receptive element such as a photoconductor receives the reflected light from an object and controls the lighting time of the electronic flash device, if the light receptive element does not receive the light transmitted only through the objective lens and the iris aperture, the iris aperture setting will not affect the automatic light adjusting means. Therefore, the lighting of the electronic flash device for obtaining an appropriate exposure cannot be automatically controlled, and it becomes necessary to manually set the aperture information separately into the electronic flash control circuit.